diff --git a/proto/test/ast_pb2_test.py b/proto/test/ast_pb2_test.py
new file mode 100644
index 0000000..f82453d
--- /dev/null
+++ b/proto/test/ast_pb2_test.py
@@ -0,0 +1,28 @@
+# Copyright 2016 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file or at
+# https://developers.google.com/open-source/licenses/bsd
+
+"""Tests for ast_pb2 functions."""
+
+from __future__ import print_function
+from __future__ import division
+from __future__ import absolute_import
+
+import unittest
+
+from proto import ast_pb2
+from proto import tracker_pb2
+
+
+class ASTPb2Test(unittest.TestCase):
+
+  def testCond(self):
+    fd = tracker_pb2.FieldDef(field_id=1, field_name='Size')
+    cond = ast_pb2.MakeCond(
+        ast_pb2.QueryOp.EQ, [fd], ['XL'], [], key_suffix='-approver')
+    self.assertEqual(ast_pb2.QueryOp.EQ, cond.op)
+    self.assertEqual([fd], cond.field_defs)
+    self.assertEqual(['XL'], cond.str_values)
+    self.assertEqual([], cond.int_values)
+    self.assertEqual(cond.key_suffix, '-approver')